1. Humidity affects the weight of your bridge. Keep your bridge in a closed container with a few grains of rice.
2. Go easy with the glue bottle. As a general rule of thumb, if you can see it than you are using too much.
3. Keep your hands clean! Oils and grease from your skin can [...]

Now Updated and Expanded
I wrote an ebook, 5 Steps to Building a Model Bridge PDF to answer the most common questions people have about building bridges. In the ebook I show all the steps of building a model bridge, and then walk people through the actual construction of a bridge. The ebook contains many photos [...]

The concept of stiffness is one I have been delving into this year. The stiffness of the wood you use directly translates into the strength of your bridge. Density no longer matters much, and is almost not worth calculating unless you can find a relationship between density and stiffness. I have not been able to [...]

Balsa wood is unique from all other woods. Its properties make it valuable to bridge builders, wood carvers, surfers, and many others.

My favorite article about Balsa wood was taken down, but I found a copy of it at Archive.org.
Balsa or Basswood?
I have heard a lot of people claim that nobody should use Balsa. They claim [...]

I have developed a system for bending wood for my arch bridges, and though I do not claim it is the best way, it works well for me.

I have a pot, or basin rather, that is about 18″ long and 12″ deep. I fill it with about two cups of water (I have found that [...]

The type of joint you use on your bridge can drastically change its strength. These pictures are not of glued joints, I simply laid sticks together. On a bridge, you want to make sure that the joints are clean and there are no gaps between the wood. Glue does not work well as a filler, [...]

Hey everybody once again it’s me, First Timer. I thought the one thing that would make this website even better would be some vocabulary on the parts of bridges. Here are a few terms that might help if you ever need to describe different aspects of a truss or bridge

What you want to look for in glue:

Drying time
Price
Weight
Strength

CA Glue. This is a very common glue used for a variety of projects. It dries in seconds, like super glue. It is also widely available. Numbers of hobby stores and online companies sell it. However, it is not cheap. CA glue can be bought in three [...]

There are several reasons you should cut your own strips of wood:

It saves money
It saves time
Helps you get familiar with the wood
Increases your skills as a builder

Video Tutorial

Video is about 4 minutes long.

DISCLAIMER:
I am not responsible for any injury caused by someone using this technique. I recommend that students cut strips of wood only [...]

Hey guys it’s me again, First Timer. I came up with a good way to practice bridge building either before or for the next competition and/or just to keep your bridge building skills good, whether it be science fair or science olympiad. It’s building different bridge designs with K-NEX, Erector Sets, and/or LEGOs. Most of you probably own one or more of the following and it really helps practicing basic truss design

I want to put x-shaped supports on my bridge, but I don’t know how best to join them. I’ve heard of something, I think it’s called a half-lap joint, that I think might work best. You cut half of the wood off the part of the strip that will be the actual joint, and then connect the two pieces at those joint parts. There isn’t any part of the wood sticking out, and they are very connected, I think, as far as how the weight/force is distributed, which I figured would be good. But is there a better way to make an x

I think it is time for me to build a popsicle stick house. I have built plenty of popsicle bridges, and even a popsicle boat. This collection would not be complete without a popsicle house.

I think I am going to stay simple with the design of the house. No fancy roofs or windows. Perhaps I [...]

I have built three different models of popsicle bridges. You can check out each one:
Popsicle Bridge #1
Popsicle Bridge #2
Popsicle Bridge #3
Popsicle bridges provide a unique challenge because of the limited length of the popsicle sticks. This hurts the inherent strength especially in tension. Ideally, a member of the bridge in tension would be one [...]

Not all popsicle sticks are equal

If you have been given a project of building a popsicle stick bridge, there is something you should know. Probably one half of the popsicle sticks that come from Wal-Mart or other store are bent, twisted, or otherwise deformed. And obviously deformed popsicle sticks won’t be as strong as straight [...]

This is the first in reviving my question and answer posts. When I receive a well asked question, I will answer it and post some of the dialogue here.

These two questions are dealing with making an elevated bridge, very similar to the Science Olympiad challenge.

Objective: To build a boomilever with the greatest efficiency.
Basic Design:
There are two basic types of boomilevers. First is the tension boomilever, where the tension chord is longer than the compression chord.

Second there is the compression boomilever, which is the opposite of the tension.

It is generally accepted that the tension boomilever is inherently better than the [...]

This tower was 24 inches tall, 6 inches wide at the base, tapering to a 1 & 1/2 inch square at the middle. This tower weighed 7.0 grams, and held 11kg for 2nd place at the 2005 GA Science Olympiad State Finals.

I am in the middle of building a tower for my Science [...]

There are several ways to test model bridges:

With a machine
By pouring sand
Textbooks
Pushing down on your bridge

Using a machine

Obviously, if a machine is being used to test your bridge, there isn’t a lot you can do. You can stand watching the destruction of your bridge. Or turn away and cover your eyes with your hands. I [...]

I have never built a toothpick bridge before, as I thought it would be too much of a hassle. However, when I came across a toothpick bridge kit I knew it was time for me to try building one.I purchased the kit, and am very pleased and surprised at its contents. The kit contains everything [...]

This is the absolute best video I have seen about building model bridges. Roy Coleman, the founder of the International Bridge Building Contest, gives a very informative presentation in this video. The presentation is over an hour long. He shows how to build a bridge from scratch. He is gearing his video towards the Chicago Regional Contest in particular. The concepts, however, apply to virtually all model bridge building projects. This is a great companion video to my 5 Steps to Building a Model Bridge ebook

I am constantly asked whether balsa is better than basswood. Here are some of my notes comparing the two woods.
Balsa is cheaper and more available than basswood. This means you can buy more wood, and build more bridges for the same amount of money. By building more, you will gain valuable experience and improve your [...]